The present invention generally relates to a steering lock assembly and, more particularly, to a steering lock assembly of a type utilizing a cylinder lock and a steering shaft lock operatively associated with the cylinder lock for selectively locking and unlocking an automobile steering shaft.
An example of a prior art steering lock assembly which appears to be pertinent to the present invention is shown in FIG. 1 of the accompanying drawings in a longitudinal sectional view, reference to which will first be made for the discussion of the prior art.
The prior art steering column lock assembly shown in FIG. 1 comprises a lock housing 3 including a cylindrical extension 1 and a generally U-shaped mounting part 2 through which the lock assembly is secured to an automobile steering column through which a steering shaft rotatably extends. The cylindrical extension 1 accommodates a cylinder lock 4 at one end thereof and an iginition switch assembly 5 at the opposite end thereof and also accommodates a locking bolt 6, which can selectively protrude into and retract from the U-shaped recess in the mounting part 2 in a direction perpendicular to the longitudinal axis of the cylindrical extension 1 respectively for locking and unlocking the steering shaft, which locking bolt 6 is located within an intermediate space between the cylinder lock 4 and the ignition switch assembly 5. This locking bolt 6 is normally biased by a compression spring 7 so as to assume a locked position in which the locking bolt protrudes into the U-shaped recess to lock the steering shaft and is operatively coupled to a cam member 8 rotatable together with the plug of the cylinder lock 4, said cam member 8 having an actuating projection integrally formed therewith and operatively coupled to a rotor 9 of the ignition switch assembly 5 for controlling the latter according to the direction of rotation of the plug of the cylinder lock 4 which is effected by turning a mating key inserted in the plug of the cylinder lock 4.
The prior art lock assembly also comprises, although not shown, a retaining mechanism for retaining the locking bolt 6 in an unlocked position once the locking bolt 6 has been moved thereto by the rotation of the plug of the cylinder lock 4 in one direction and so long as the key is not removed or withdrawn from the plug of the cylinder lock 4 even though the latter has subsequently been rotated in the reverse direction back to the original position.
In the construction described above and shown in FIG. 1, a relatively complicated and time-consuming procedure is required to assemble the various component parts together to provide a complete steering lock assembly. By way of example, relative to the cylindrical extension 1, the cam member 8 and the cylinder lock 4 are successively inserted in a direction shown by arrow A into one end of the cylindrical extension 1, the locking bolt 6 and the compression spring 7 are successively inserted in a direction shown by arrow B, and the ignition switch assembly 5 is mounted in the direction shown by arrow C and counter to the mounting direction A. This three-direction assembly system requires not only a complicated and time-consuming procedure, but also an increased number of component parts of the lock assembly which in turn results in an increased weight of the lock assembly.
Specifically, the three-direction assembly system requires the use of separate fixing elements or fixtures to hold the respective component parts in position and, depending on the arrangement of the fixtures, some component part of the lock assembly have to be separate members. This will be explained by way of example with further reference to FIG. 1.
In order to secure a sufficient stroke of movement of the locking bolt 6 between the locked and unlocked postions, the plug of the cylinder lock 4 and the cam member 8 have to be separate members and such is the case with the prior art lock assembly shown in FIG. 1. In addition, in order to connect the plug of the cylinder lock 4 effectively with the cam member 8 so that the rotation of the plug of the cylinder lock 4 can be transmitted to the locking bolt 6 through the cam member 8, that portion of the cam member 8 which is connected to the plug of the cylinder lock 4 must be of a relatively large diameter, requiring the employment of a relatively large chamber in the cylindrical extension 1 for the accommodation of the cylinder lock 4 so that the cam member 8 can be inserted into the intermediate space through the large chamber. The employment of the large chamber for the cylinder lock 4 necessitates the employment of a cylinder portion 13. The cylinder portion 13 forms a part of the cylinder lock 4 together with the plug rotatably housed within the sleeve 13 and is, after having been inserted into the large bore in the extension 1, held in position by means of one or more cotter pins 14. Furthermore, in order to retain the ignition switch assembly 5 in position inside the lock housing 3 at a position on one side of the locking bolt 6 opposite to the cylinder lock 4, the lock housing 3 is required to be provided with a partition wall 15 separating the intermediate space from a chamber for the ignition switch assembly 5 and to which the ignition switch assembly 5 is, after having been inserted into such chamber, engaged to assume a proper position inside the lock housing 3.
Apart from the prior art steering lock assembly of the construction shown in FIG. 1, the British patent specification No. 1,512,809, published on June 1, 1978, discloses a steering lock wherein the cam member is integrally formed with the plug forming a part of the cylinder lock. However, the cam member used therein is of a size larger in diameter than the plug and, therefore, the cylinder lock used therein necessitates the employment of the cylinder portion discussed above.
A cylinder lock which does not require the use of the cylinder portion is disclosed, for example, in the British patent specification No. 1,455,444, published on Nov. 10, 1976. However, since this patent specification is directed to means for preventing the plug of the cylinder lock from being removed by an unauthorized person, this patent specification is silent as to the details of how the cylinder lock is operatively associated with the locking bolt.